This invention relates to internal combustion engines, including but not limited to fuel governors for internal combustion engines.
Fuel governing functions for internal combustion engines such as diesel engines is known. Fuel governors are utilized to determine how much fuel to provide to the fuel injectors and make ongoing adjustments to the fuel values. Engines typically have three modes: no start (mode 0), cranking (mode 1), and running (mode 2).
During the time when an engine starts to crank, a certain amount of fuel is utilized to turn the engine over, i.e., to cause the engine to reach desired engine speed. Once the engine turns over and begins running in a steady state condition, a lesser amount of fuel is needed than the amount of fuel needed during engine crank.
At various times, the amount of fuel change between cranking and running the engine is substantial. Such a condition is magnified during cold weather or during long sustained cranking due to other engine problems. When such a large change in fuel provided to the engine occurs, a number of undesirable events may occur. A timing diagram illustrating these events according to engine speed, fuel, and engine mode is shown in FIG. 1.
As shown in the left side of FIG. 1, once reaching running mode is achieved, the fuel amount is reduced, causing the engine to stumble or hesitate. Additional fuel is added, but the added fuel is not enough to maintain engine speed. When the engine speed drops too far, the engine stalls, requiring another crank cycle, thereby wasting fuel. As illustrated in the far right side of FIG. 1, the added fuel prompts the engine to overshoot its desired speed, setting off oscillation in both engine speed and fuel supplied, which in turn causes the engine to fluctuate between cranking and running modes, resulting in the engine running in a rough manner until the oscillation ceases.
Accordingly, there is a need for a fuel governor that reduces or eliminates engine stumbling, hesitation, stalling, and other undesirable events when significant changes in fuel provided to an engine occur.
A method of delivering fuel to an engine includes the steps of detecting an engine mode change from cranking mode to running mode and determining a step fuel amount. In response to the step of detecting, the step fuel amount is delivered to the engine during a step time. When the step time expires, a fuel amount generated by the fuel governor is provided to the engine.